Hi,
I am looking all over the internet for a guide or website to look up part numbers for my car, unfortunately couldn't find any.

Without knowing the part number it's really confusing, too many models on Ebay and can't tell if the part will fit on my car or not

For instance I am looking for Oxygen sensor (Front) part number for my Vw Bora V6 4Motion 2001 . How would you find the part number?